No abstract available

[en] In this present article we have established an expression for the temperature dependence of the lattice thermal conductivity of solids with harmonic disturbances. The relaxation rate for scattering of phonons with point defect is also derived. We will apply the Kubo-correlation function formalism for the thermal conductivity, and the double time temperature dependent Green function technique for the evaluation of correlation functions

[en] Electric vehicle batteries use energy and generate environmental residuals when they are produced and recycled. This study estimates, for 4 selected battery types (advanced lead-acid, sodium-sulfur, nickel-cadmium, and nickel-metal hydride), the impacts of production and recycling of the materials used in electric vehicle batteries. These impacts are compared, with special attention to the locations of the emissions. It is found that the choice among batteries for electric vehicles involves tradeoffs among impacts. For example, although the nickel-cadmium and nickel-metal hydride batteries are similar, energy requirements for production of the cadmium electrodes may be higher than those for the metal hydride electrodes, but the latter may be more difficult to recycle

[en] ZnSe films were prepared by a stacked elemental layer deposition method on glass substrates at a pressure 10^-5 Torr. The films were rapid thermal annealed (RTA) using halogen a lamp for different times to get a homogeneous structure of ZnSe thin films. The films were found to be p-type in nature. The band gap was found to vary with annealing time due to removal of defects and increase grain size of films. It was also observed by X-ray diffraction (XRD) pattern that the grain size of films increase with annealing time. The lattice constant for cubic structure of these films was found to be a = 5.72 A. Rutherford back scattering data also confirmed mixing of the elements with annealing time

No abstract available

[en] The potential peaking of world conventional oil production and the possible imperative to reduce carbon emissions will put great pressure on vehicle manufacturers to produce more efficient vehicles, on vehicle buyers to seek them out in the marketplace, and on energy suppliers to develop new fuels and delivery systems. Four cases for stabilizing or reducing light vehicle fuel use, oil use, and/or carbon emissions over the next 50 years are presented. Case 1-Improve mpg so that the fuel use in 2020 is stabilized for the next 30 years. Case 2-Improve mpg so that by 2030 the fuel use is reduced to the 2000 level and is reduced further in subsequent years. Case 3-Case 1 plus 50% ethanol use and 50% low-carbon fuel cell vehicles by 2050. Case 4-Case 2 plus 50% ethanol use and 50% low-carbon fuel cell vehicles by 2050. The mpg targets for new cars and light trucks require that significant advances be made in developing cost-effective and very efficient vehicle technologies. With the use of alternative fuels that are low in carbon, oil use and carbon emissions can be reduced even further

[en] Recent studies have indicated that substitutes for conventional petroleum resources will be needed to meet U.S. transportation energy demand in the first half of this century. One possible substitute is natural gas which can be used as a transportation fuel directly in compressed natural gas or liquefied natural gas vehicles or as resource fuel for the production of hydrogen for fuel cell vehicles. This paper contains a preliminary assessment of the availability of U.S. natural gas resources to meet future U.S. transportation fuel demand. Several scenarios of natural gas demand, including transportation demand, in the U.S. to 2050 are developed. Natural gas resource estimates for the U. S. are discussed. Potential Canadian and Mexican exports to the U.S. are estimated. Two scenarios of potential imports from outside North America are also developed. Considering all these potential imports, U.S. natural gas production requirements to 2050 to meet the demand scenarios are developed and compared with the estimates of U.S. natural gas resources. The comparison results in a conclusion that (1) given the assumptions made, there are likely to be supply constraints on the availability of U.S. natural gas supply post-2020 and (2) if natural gas use in transportation grows substantially, it will have to compete with other sectors of the economy for that supply-constrained natural gas

[en] Small angle neutron scattering (SANS) has been used to study the size and ordering of the pore structure of mesoporous silica. Mesoporous silica was synthesised in the presence of a 16 carbon chain surfactant, cetyl-trimethyl ammonium bromide (CTAB) using the sol-gel method. The SANS patterns of the mesoporous silica were measured on samples before and after calcination. Calcination at 600 deg. C for 2 h results in removal of the surfactant template. The SANS study revealed the presence of an ordered pore structure with pore spacing of approximately 3.5 nm. After calcination the pore spacing decreased. Using the SANS technique it was possible to quantify the pore sizes and pore spacing and then determine the wall thickness

[en] The polarographic behaviour of UO₂(II) has been studied in different supporting electrolytes of varying concentrations. On applying various criteria for ascertaining the irreversible nature of the polarographic reduction, it has been found that the reduction at both the steps of UO₂(II) at d.m.e. is totally irreversible. Koutecky's treatment has been applied to calculate the rate constant at various potentials along the course of a polarogram in the presence of different concentrations of the supporting electrolytes. The values of the kinetic parameters have been calculated at different concentrations of the supporting electrolytes. A quantitative interpretation in terms of the values of the kinetic parameters is proposed to explain the influence of concentration and nature of the supporting electrolytes. (author)

[en] Rn²²² (radon) from Ra²²⁶ (radium) and two other natural isotopes of Rn²¹⁹ (actinon) and Rn²²⁰ (thoron) are present in any rock formation in the soil, in groundwater and in the atmosphere. The inert gases, such as radon, are poorly affected by chemical equilibration processes and are often considered in earthquake prediction because of the high mobility characteristics, high natural production rate and relative low price of automatic monitoring analytical equipment. This study deals with the monitoring of radon in groundwater wells, groundwater table depth and water temperature for the year 1997. The daily oscillations of radon levels have been recorded with instantaneous technique using ZnS(Ag) detector from the borehole at Amritsar, India (31 deg. 35'N, 74 deg. 56'E). Significant increases in radon concentration of groundwater and water level have been observed which are correlated to the seismic events which occurred in Northern India during the period of study. The correlation between the radon levels and water table depth as well as water temperature is also discussed